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Investigating the structural characterization of amorphous mineral precursors for enhanced understanding of contaminant adsorption and incorporation
Abstract   Open access   Peer reviewed

Investigating the structural characterization of amorphous mineral precursors for enhanced understanding of contaminant adsorption and incorporation

Samangi Abeysinghe and Tori Z Forbes
Mineralogical magazine, Vol.76(6), p.1713
Goldschmidt 2012
2012
DOI: 10.1180/S0026461X00008434
url
https://doi.org/10.1180/S0026461X00008434View
Published (Version of record) Open Access

Abstract

Metal oxyhydroxide mineral phases, particularly those containing Fe(III) or Al(III), play an important role in determining the long fate and transport of heavy metals and radionuclides in environmental systems. During rapid hydrolysis of the metal in solution, an amorphous or poorly crystalline precipitate initial forms, which can further transform into a thermodynamically stable mineral phase. During aggregation and flocculation processes, contaminants can adsorb to the surface of the particles, leading to co-precipitation and incorporation. Therefore, understanding the relationship between the soluble molecular precursor species present in solution and the amorphous precipitate is vital for gaining a molecular-level understanding of contaminant uptake by mineral species. To investigate the structural relationship between the soluble precursors and the amorphous phase, we have begun synthesizing geochemical model compounds to compare to X-ray scattering of the amorphous phase. These model phases are metal oxyhydroxide nanoclusters that are 1-2 nm in diameter that can be packed into an ordered lattice for structure determination via single-crystal X-ray diffraction. The Pair Distribution Function (PDF) analysis of the module compounds can be calculated and compared to experimentally derived spectra. In this presentation we will focus on the relationship between aluminum based nanoclusters and amorphous aluminum hydroxide. In addition, geochemical model compounds with adsorbed contaminants will also be discussed that may provide information regarding possible adsorptions sites within amorphous materials.
 Amorphous Materials Iron aluminum chemical composition crystal structure Environmental geology flocculation heavy metals hydroxides lattice metals Mineralogy of non-silicates oxides oxyhydroxides pollutants pollution thermodynamic properties

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